Optical surfaces for softening a light/dark border of a lighting device for vehicles are known from DE 10 2008 023 551 A1, which are provided with a grid of lens elements distributed on a base surface thereof. The lens elements completely cover the base surface of the optical surface designed as a lens surface. The contour of the lens elements is calculated according to a mathematical function, from powers of angular functions, for example. As a result, it should be possible to obtain a targeted adjustment of the properties of the light/dark border in a light distribution from motor vehicle lighting devices. In particular, it should be possible to adjust the degree of softening of the light/dark border in a targeted manner. The disadvantage with the known optical surface is that the production expenditures for the shaping of the optical surface according to the mathematical functions are relatively high.